Detergent alkylate treating process



United States Patent 3 501,543 DETERGENT ALKYIiATE TREATING PROCESS George L. Hervert, Downers Grove, Ill., assignor to Universal Oil Products Company, Des Plaines, Ill., a corporation of Delaware No Drawing. Filed Nov. 8, 1966, Ser. No. 592,760 Int. Cl. C07c 7/00 US. Cl. 260-674 Claims ABSTRACT OF THE DISCLOSURE The fluoride content and/or olefin content of a detergent alkylate can be reduced by treatment with substantially anhydrous hydrogen fluoride in the liquid phase.

This invention relates to the treating of detergent alkylates prior to the introduction of a hydrophilic group therein to reduce the fluoride content and bromine index thereof. If the fluoride content is not reduced, then when the detergent alkylate has a hydrophilic group introduced therein such as by sulfonation, the final detergent becomes discolored and may contain a disagreeable odor. It has .been found that the treatment of the detergent alkylate with HF within a critical temperature range is effective in reducing the fluoride content and/or bromine index.

In one of its embodiments, this invention relates to a process for treating a detergent alkylate which comprises contacting the detergent alkylate with substantially anhydrous hydrogen fluoride in the liquid phase at temperatures of from about 90 F. to about 150 F. and recovering the treated detergent alkylate.

Detergents essentially are composed of a complex molecule containing both a hydrophobic group and a hydrophilic group. The purpose of the hydrophilic group is to render the detergent molecule water soluble. The hydrophobic group solubilizes grease, dirt, etc. and thus .aids in the cleaning step in which detergents are employed.

A proper detergent molecule contains a proper balance between hydrophilic and hydrophobic groups in order to produce a detergent having the proper cleaning characteristics. The hydrophobic group is generally supplied -by an organic hydrocarbon. It is known that the hydrophobic group is readily supplied .by an alkylaryl group wherein the alkyl portion is a saturated hydrocarbon having from about 10 to about carbon atoms (C to C and preferably about 12 to 13 carbon atoms and the aryl portion is a mono-nuclear aromatic ring. These alkylaryl compounds are readily prepared by alkylation of a mononuclear aromatic hydrocarbon with a mono-olefin hydrocarbon having from about 10 to about 15 carbon atoms per molecule. The resulting monoalkylate product is called detergent alkylate. This detergent alkylate is rendered surface active by introducing a hydrophilic group into the aryl ring as for example by sulfonation and neutralization with caustic to produce the sodium alkylbenzene sulfonate detergent. The alkylation is carried out over an acid catalyst. A preferred acid catalyst is hydrogen fluoride. However it has been found that the detergent alkylate produced from a hydrogen fluoride catalyzed alkylation reaction can discolor and cause a disagreeable odor when converted to the final detergent product by sulfonation.

It is an object of this invention to treat detergent alkyl ate such that when said alkylate is converted to a detergent, compound formation which discolor and add a disagreeable odor to the detergent is minimized.

It is another object of this invention to reduce the olefinic content of detergent alkylate.

It is still another object of this invention to reduce the fluoride content of the organic phase produced from a hydrogen fluoride catalyzed alkylation zone.

These and other objects will become more apparent especially in the light of the following detailed description.

Detergent alkylates of the alkylaryl variety are prepared by alkylation of a mono-nuclear aromatic molecule with a mono-olefin having from about 10 to about 15 carbon atoms per molecule. The mono-nuclear aromatic is preferably selected from the group consisting of henzene, toluene, xylene, ethylbenzene, methylbenzene, diethylbenzene, mononitrobenzene and phenol. Benzene is especially preferred. The mono-olefins are preferably prepared from petroleum or petroleum derived fractions in the C to C carbon number boiling range. This is readily accomplished by separating the parafiins in a kerosene fraction by techniques such as adsorption of the more polar components such as aromatics and naphthenes over a selective sorbent such as silica gel, activated carbon, molecular sieves or by the use of a selective solvent. In any event a relatively pure parafiin fraction in the C -C boiling range is obtained. These paraflins may be converted directly to mono-olefins by dehydrogenation over a suitable dehydrogenation catalyst or the paraflins may indirectly be converted to mono-olefins by a halogenation step followed by a dehydrohalogenation step. In some cases it is preferred only to use the normal or straight chain paraffins so as to produce a linear alkyl 'benzene sulfonate detergent since these detergents are more readily biodegradable in subsequent sewage treating. When dehydrogenating the straight chain paraflins to produce straight chain mono-olefins the dehydrogenation catalyst must be of low acidity or preferably neutral or basic in order to minimize isomerization of the straight chain paraflins or, straight chain mono-olefins. Straight chain paraflins are readily separated from kerosene mixtures in a suitable contacting apparatus containing molecular sieves having a pore opening of about 5 angstroms in diameter. A preferable process to attain this separation is that shown in US. Patent No. 2,985,589. Another source of suitable mono-olefins is the so-called tetramer fraction formed from the polymerization of propylene. Tetramer is produced by contacting a hydrocarbon stream containing propylene over a suitable polymerization catalyst such as solid phosphoric acid at polymerization conditions and fractionating the polymerized product to produce a fraction boiling in the C to C boiling range.

The mono-olefins are admixed with the mono-nuclear aromatic such as benzene and introduced into an alkylation reaction zone. Preferably, excess benzene (relative to mono-olefin) is employed in order to promoe the mono-alkylation reaction. Therefore the alkylation reactor effluent contains an appreciable amount of benzene which is separated by fractionation and recycled to the alkylation reactor. When the mono-olefins are formed from the dehydrogenation of paraflins there will also be appreciable amounts of unreacted paraflins in the C C carbon number range in the alkylation reactor effluent which are separated from the detergent alkylate by fractionation and recycled to the dehydrogenation step. The alkylation reaction is catalyzed by an acid, peferably hydrofluoric acid. Although hydrofluoric acid is a very effective catalyst for this reaction it also is responsible for compound formation which can cause discoloration and disagreeable odor to the finished detergent formed from the detergent alkylate. Also when paraflins are recycled to the dehydrogenation zone, fluoride compounds can affect the dehydrogenation catalyst adverse- 1y. When straight chain paraffins are dehydrogenated over a low acid or non-acid catalyst such as platinum on a-lkalized alumina to form straight chain mono-olefins, if the recycled straight chain paraffins contain fluoride compounds, the dehydrogenation catalyst can pick up fluoride which will increase the acidity of the catalyst. The increased acid dehydrogenation catalyst can cause undesirable reactions to occur such as isomerization of the straight chain paratfins or olefins thus frustrating the object of producing biodegradable detergents.

It has been found that if the organic phase from the alkylation zone or alternately the separated detergent alkylate is contacted with substantially anhydrous hydrogen fluoride at temperatures of from about 90 to 150 F., there will be a decrease in olefinic and fluoride content which in turn will allow the production of detergents free of discoloration and disagreeable odors. By substantially anhydrous hydrogen fluoride, I means that the hydrogen fluoride is of high purity that is above 90% by weight and preferably above about 95% by Weight. Especially preferable are hydrogen fluoride purities in excess of 98% by Weight. This is accomplished either by separating the excess benzene and paraifins (if present) and contacting the detergent alkylate with hydrogen fluoride at temperatures within the critical range, directly contacting the total organic eflluent from the alkylation zone with hydrogen fluoride at temperatures within the critical range or maintaining the alkylation zone or at least the latter part of the alkylation zone at temperatures within the critical range. This will result in the ultimate production of satisfactory detergent. Suitable contact times between the detergent alkylate and the treating hydrogen fluoride is from about 2 to 3 minutes to about 24 hours. It has been found that a temperature of about 100 F. is the most preferable within the critical temperature range.

The following examples are presented hereinbelow to more fully illustrate the present invention.

EXAMPLE I Detergent alkylate is produced by alkylating benzene with propylene tetramer in the presence of hydrogen fluoride catalyst at temperatures of about 45 F. The alkylation product is fractionated removing benzene overhead and producing a detergent alkylate concentrate having a bromine index equal to 239. This concentrate is blended with benzene in sufficient amounts to reduce the bromine index to 60. A reactor is constructed out of a 24" length schedule 80 2 stainless steel pipe fitted with welding caps at each end having entrances therein. The reactor is filled with iron chain links having dimensions of by An inlet line is attached at the bottom of the reactor and contains a sintered metal disc to disperse the incoming feed. The reactor is filled with 1123 grams of 100% hydrogen fluoride. The pressure is maintained at about 100 p.s.i.g. and the temperature is held at about 100 F. The detergent alkylate containing benzene having a bromine index of 60 is introduced into the reactor at a rate of about 278 cc./hr. The organic phase is withdrawn from the top of the reactor whereupon subsequent analysis reveals the bromine index to be 15. After one hour, the charge rate is increased to 304 cc./hr. and the resulting bromine index of the treated material is 13. Finally the charge rate is reduced to 283 cc./hr. and the resulting bromine index is 11. Thus it is seen that there has 'been a fourfold decrease in bromine index thus showing a marked decrease in olefinic content.

The organic eflluents from these three runs are combined and subjected to fractionation into various cuts.

The untreated feed (the material with the 60 bromine index) is also fractionated into similar cuts and these cuts are subjected to bromine index analysis. The results are summarized in Table 1 below.

TABLE I Treated Material Charge Product Overall bromine index 60 -13 Composition, volume percent:

1B P212 F 71. 8 69. 9 212338 F- 0. 4 0.3 338-480 F- 2. 9 3. 2 480585 F- 20. 8 21. 3 585-623 F 1. 3 1. 3 623 a 3. 3 4.0 Bromine index of fractions:

B P212 F. benzene fraction 3. 3 1. 8 212-338 F. by-product 234 297 338-480 F. by-product and light alkylate. 586 82 480585 F. detergent alkylate 129 39 585 623 F. detergent alkylate and heavy alkylate 151 141 623 F. heavy alkylate 843 409 Fluorine content detergent alkylate (480-585) wt. p.p.m 16 7 Inspection of the results of Table I show not only that the hydrogen fluoride is effective in reducing the olefinic content (as measured by bromine index) of the overall detergent alkylation mixture including by-product from an alkylation step but also that this treatment is especially selective in the reduction of olefinic content of the material in the boiling range of detergent alkylate. Thus the results show a three fold reduction in bromine index in the detergent alkylate material whereas no significant improvement in the 2l233-8 F. fraction and the 585- to 623 P. fraction. It should also be noted that the treatment is eifective in reducing the fluoride content of the detergent alkylate by over a factor of two.

EXAMPLE II This example is presented to show the importance of temperature in the process of the present invention. A polymerized propylene stream having an initial boiling point of 370 F. and an end point of'500" F. is introduced into a hydrogen fluoride alkylation reactor along with suflicient benzene to maintain a benzene to olefin mole ratio of about 8.4. The hydrogen fluoride is maintained at a purity of about 93-94 percent and contains about 2-3 percent water. The operating conditions maintained in the reaction zone are as follows: pressure-A00 p.s.i.g.; space time11.5 to 11.8 minutes; acid to hydrocarbon volume ratioabout 1.0; and Reynolds number about 4000. Two runs are made at the above conditions, the first at an alkylation zone temperature of F. and the second at an alkylation zone temperature of 45 F. The organic phase from the alkylation zone is recovered and fractionated to remove benzene overhead. The benzene column bottoms are analyzed for bromine index. The bromine index of benzene column bottoms from the 100 F. alkylation zone run is 2'8 and the corresponding benzene column bottoms bromine index of the 45 F. alkylation zone is 218. Thus when contacting the detergent alkylate with hydrogen fluoride at temperatures of 45 F. there is almost an eightfold increase in olefinic content over the run at temperatures of 100 F.

EXAMPLE III This example is presented to show the importance of the purity of the hydrogen fluoride in effectively treating the detergent alkylate. A polymerized propylene fraction having an initial boiling point of 365 F. and an end point of 474 F. is introduced into an alkylation zone and alkylated with benzene in a manner similar to that of Example II. The results and operating conditions are summarized below in Table II.

Acid to hydrocarbon volume ratio Reynolds number 4, 000 4, 000 Propelratli els of benzene column bottoms:

Boiling range, F.

Bromine index .0. 3

Examination of the results of runs 1 and 2 clearly show the desirability of maintaining high purity hydrogen fluoride in the treating step since a reduction in purity of 13% resulted in a ninefold increase in bromine index.

EXAMPLE IV Another batch of detergent alkylate is prepared by separating straight paraflins from a kerosene boiling range hydrocarbon by means of molecular sieves having pore openings of about 5 angstroms. The normal paraflins are introduced into a fixed bed reactor containing a catalyst having 0.75 weight percent platinum, 0.5 weight percent lithium and an arsenic to platinum atomic ratio of 0.47 on a porous gamma alumina support. The operating conditions maintained in the reactor are catalyst bed inlet temperatures of 475 C., a pressure of p.s.i.-g., a hydrogen to hydrocarbon mole ratio of 8.0 and a liquid hourly space velocity of 16.0. The results show a conversion 01 21.4% with a selectivity of 84.1% to straight chain monoolefins. The normally liquid dehydrogenation reactor effluent, after separation and recycle of a hydrogen rich gaseous phase, is introduced into an alkylation zone along with sufficient benzene such that the benzene to olefin mole ratio is about 10:1. Hydrogen fluoride is added to the alkylation zone to provide a HF/hydrocarbon (excluding the normal paraffins) volume ratio of about 1.511 and the zone is maintained at 100 F., a pressure of about 250 p.s.i.g. and a contact time (between HF and hydrocarbons) of slightly less than two minutes. The hydrocarbon portion of the alkylation product efliuent is separated from the hydrogen fluoride catalyst by washing and stripping and is sent into a fractionation column wherein a benzene portion, a normal paraffin portion and an alkylate portion are separated. The benzene portion is recycled to the alkylation zone, the normal paraflin portion is recycled to the dehydrogenation zone and the alkylate is recovered. The run is continued until 5 barrels per pound of dehydrogenation catalyst have passed through the dehydrogenation zone. Thereafter the temperature in the alkylation zone is lowered to about F. whereupon shortly thereafter the presence of branched chain detergent alkylate is noted. Also during. this latter operation when the detergent alkylate is converted to the sodium sulfonate detergent, significant amounts of color bodies are present which discolors the detergent product.

I claim:

1. A process for treating detergent alkylate containing at least one impurity selected from the group consisting of fluorides and olefins which comprises contacting said detergent alkylate with a fluoride-content reducing and olefin-content reducing agent consisting essentially of substantially anhydrous hydrogen fluoride in the liquid phase at temperatures of from about F. to about 150 F. and recovering the treated detergent alkylate.

2. The process of claim 1 further characterized in that the detergent alkylate is derived from the alkylation of an aliphatic mono-olefin having from about 10 to about 15 carbon atoms per molecule and a mono-nuclear aromatic.

3. The process of claim 2 further characterized in that the aliphatic mono-olefin is propylene tetramer.

4. The process of claim 2 further characterized in that the aromatic is selected from the group consisting of benzene, toluene, xylene, ethylbenzene, methylethylbenzene, diethylbenzene, mono-nitrobenzene and phenol.

5. The process of claim 2 further characterized in that the treating temperature is about F.

References Cited UNITED STATES PATENTS 2,851,503 9/1958 Shiffier 260-671 DELBERT E. GANTZ, Primary Examiner C. R. DAVIS, Assistant Examiner US. Cl. X.R. 

